Dr Radhakrishnan said studies have been initiated on the re-usable launch vehicle (RLV) with plans for a lift-off of the technology demonstrator in two years. “We have to understand a gamut of technologies and also prove many new systems. We have to study the aerodynamics of a winged body, the auto pilot, the aero-thermo dynamics, thermal protection system, the de-boost operations for re-entry, navigation and guidance to land precisely on the ground. Of course, some of the lessons learnt from the space shuttle will be incorporated in this vehicle,” he added.

Along with the RLV, Isro would also test air-breathing technology using a scramjet fitted on a sounding rocket in the next couple of years.

One of the biggest false lessons from STS was that are not practical.The Shuttle was unpractical because it was a jack of trades and was too complex.It's good to see that ISRO sees the real lesson from STS.

Everyone talks about China dominating space but I think India is going to be the country to watch in the next 20 years.

ISRO chief Radhakrishnan seems to be saying that they'll explore this technology, but won't zealously/stubbornly overcommit to it.

As someone who works in IT, I'm always hearing how CIO's and architects should be technology-agnostic, and not show bias in stubbornly pursuing a particular technology or platform regardless of whether it fits or not.

So ISRO will explore this technology, but if it doesn't fit their needs, they'll pass it over.

The space agency, as a first step towards realising a Two-Stage To Orbit (TSTO) re-usable launch vehicle, has developed a winged RLV-TD....The RLV-TD will act as a flying test-bed to evaluate various technologies — hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air breathing propulsion.

The first in the series of trials is the hypersonic flight experiment (HEX) followed by the landing experiment (LEX), return flight experiment (REX) and scramjet propulsion experiment (SPEX).

During HEX, the vehicle will take lift off in the form of a rocket with a booster. Later, it can be recovered from sea.

So, it sounds like a two-stage vehicle, with a scramjet-powered recoverable first stage and a winged orbiter for a second stage.

Just to clarify, the RLV-TD is merely intended as a low-cost testbed platform, and is not intended as a prototype that later platforms would resemble.

India's ultimate goal for RLV is the AVATAR (Aerobic Vehicle for hypersonic Aerospace Transportation) which will be an SSTO (Single-Stage-to-Orbit) vehicle.

India can't make AVATAR right away, so it will first build and operate the TSTO (Two-Stage-to-Orbit) vehicle, which is composed of a lower stage and an upper stage. The lower stage is a winged flyback booster powered by a semi-cryogenic rocket, and the upper stage is powered by a cryogenic rocket.

But before India can even build TSTO, it will build RLV-TD to act as a testbed platform for the technologies which will be used by the TSTO as well as the AVATAR SSTO. For instance, the RLV-TD will also test a hypersonic scramjet engine, which is not used in the TSTO, but will be used in the ultimate AVATAR SSTO.

As a low-cost testbed (not a prototype), the RLV-TD will carry out a series of experiments: HEX, LEX, REX, and SPEX.

HEX (Hypersonic Flight Experiment) will see the RLV-TD launched on a rocket booster high above the atmosphere, and then released to glide back into the atmosphere at hypersonic velocity. Note that this will be a glide, and not an engine-powered flight, but it will be able to test the airframe and control systems. RLV-TD will then land in the ocean and be recovered.

LEX (Landing Experiment) will have the RLV-TD fitted with landing gear. It will be flown on a large transport plane and then dropped, so that it can glide down to a landing strip, deploy its landing gear and land like a regular aircraft.

REX (Return flight Experiment) will have RLV-TD fitted with jet engines that will allow it to take off from an airstrip like a regular aircraft. It will then fly around and return back to land on the strip like a regular aircraft.

Finally SPEX (Scramjet Propulsion Experiment) will have RLV-TD further fitted with a scramjet engine. It will get to take off from an airstrip like a regular aircraft, but once in flight it will accelerate to supersonic speed, after which it will activate its air-breathing scramjet engine and accelerate to hypersonic velocity. The scramjet will then switch off and the vehicle will decelerate until it can reactivate its normal jet engines and then return to land at the landing strip like a regular aircraft.

So the actual later vehicles that RLV-TD is acting as a testbed for, will look nothing like the RLV-TD itself. RLV-TD is a testbed, and not a prototype.

A bit disappointing though, that the 'Launch Vehicle Demand' chart now puts the manned vehicle 15 years into the future...

Well, the first manned flight was planned for 2016, and I think they'll probably be able to do it by 2018 at the latest. The GSLV-Mk3 will be the carrier for the first manned flights, and that will certainly be ready before then. It's mainly the crew capsule and launch abort system that remain to be done before then.

It's smaller - only takes 10 tonnes of payload to LEO - and all stages will be reusable.

Its flight profile is the inverse of the US Space Shuttle, because the booster is what glides back to Earth, instead of being thrown away. Meanwhile the more traditional-looking upper stage is what goes to orbit. However, it too would come back down to Earth for a powered vertical landing.

If you look at the diagram of the TSTO vehicle, you'll see a little red-colored section that mates the upper stage to the lower stage flyback booster. That interstage section obviously gets discarded during stage separation, and is not reused. But aside from replacing this you're only supposed to replace the fuel, as the TSTO is intended to be fully reusable in order to lower launch costs. Keeping costs down has always been a top priority for ISRO.

Ironically, the RLV-TD testbed sort of has the inverse appearance of the planned TSTO vehicle. The RLV-TD is mounted on a traditional-looking solid booster rocket which is discarded, and after separating it then glides back to Earth. But again, it's just a testbed.

RLV-TDStructural Model has been realised, which consists of fuselage nose body, fuselage straight body, a pair of double delta wings and two vertical tails. This structural assembly incorporates all the complexities of an aircraft and rocket embedded in it.

Qualification model of Radar Altimeter was realised and balloon test conducted at TIFR, Hyderabad. Carbon-carbon (C/C) laminates for nose cap were realised through a new route. Functional qualification test of Launch Hold and Release System (LHRS) with dual pyro initiation carried out with simulated interfaces.

The testing of HS9 booster stage separation system along with hydraulic line separation system was completed successfully. High altitude test of the 2 kN retro rocket developed for jettisoning spent HS9 motor was successfully conducted at SDSC SHAR.

The Integrated Technical Review (ITR) of RLV-TD by the National Review Committee in October 2012 has concluded that launch of RLV-TD HEX-01 mission in September 2013 is feasible

Iron Bird facility: This facility is second of its kind in the countryto simulate the actual flight profiles using the actuators, control electronics, the entire NGC hardware with built in NGCsoftware. The actual flight hydraulic lines will be truly represented and the control surface actuator movements also willbe simulated. This facility is used to carry out the Actuator in Loop Simulation runs for RLV-TD.

I read the update about a new manufacturing route for the nose cap CC laminates, but any news on the TPS testing? Actually, any details of the TPS at all? How re-usable is it intended to be?

The flight profile of the TSTO is also intriguing.1) Why is the 1st stage the winged booster, and the upper stage the grasshopper? Why not vice versa? Some benefit of the aerodynamic lift to the curvilinear trajectory followed in ascent?2) Why is there a different flyback mechanism for the upper stage, and the lower stage booster in any case? As it is, the diagram shows the first stage reaching altitudes+velocities where thermal protection becomes necessary for re-entry (unlike the recoverable, and reusable shuttle SRBs). Why not add a smaller version of the first stage on top of it instead of a grasshopper? I would think that two different technologies leads to increased design and development (if not operational also) costs.

Among those two, I'm biased to winged flyback over a vertical landing: cross range ability, possibly cheaper (propellant wise) control during ascent, and... well, they look the part of flying machines too

Wow! That's awesome antriksh. That looks very similar to what NASA was looking at for the cancelled Space Launch Initiative.

Thanks!! Yes the first stage is similar to the RBS concept. TSTO Hopes to achieve 100 flights per vehicle, semi-cryo engine design is targeting reputability of 15 flights. turn around time of one month.

I read the update about a new manufacturing route for the nose cap CC laminates, but any news on the TPS testing? Actually, any details of the TPS at all? How re-usable is it intended to be?

The flight profile of the TSTO is also intriguing.1) Why is the 1st stage the winged booster, and the upper stage the grasshopper? Why not vice versa? Some benefit of the aerodynamic lift to the curvilinear trajectory followed in ascent?2) Why is there a different flyback mechanism for the upper stage, and the lower stage booster in any case? As it is, the diagram shows the first stage reaching altitudes+velocities where thermal protection becomes necessary for re-entry (unlike the recoverable, and reusable shuttle SRBs). Why not add a smaller version of the first stage on top of it instead of a grasshopper? I would think that two different technologies leads to increased design and development (if not operational also) costs.

Among those two, I'm biased to winged flyback over a vertical landing: cross range ability, possibly cheaper (propellant wise) control during ascent, and... well, they look the part of flying machines too

For HEX01 TPS will be a combination of ablative, silica tiles, ceramic matrix and carbon composites and probably matellic. There is no data available on the reusability of the TPS, but it seems that ISRO is more inclined towards using metallic TPS for the TSTO. ex.

1. paper, "Manufacturing of Inconel 718 Based Honeycomb Panels for Metallic Thermal Protection Systems" 2012Abstract: Metallic thermal protection system (MTPS) offers significant improvements over the ceramic based TPS for reentry applications. Space shuttle refurbishment time is estimated to be around 17000 man hours between flights. Metallic based TPS can be fabricated easily and provides wide range of design options for TPS. Adaptability and robustness of metallic thermal protection systems offers the potential for reusability. In this work, a unique manufacturing process has been evolved to realize light weight honeycomb panels through corrugation, laser welding and diffusion brazing of faceplates, where in 50 micron thick Inconel718 foil is used for making honeycomb core and 0.2mm thick Inconel718 foil as faceplates. The compression and three point bend test on these panels have shown no debond between faceplates and honeycomb core. 150x150x5mm size honeycomb panels were coated with YSZ and NiCrAlY based Thermal Barrier Coatings (TBC) and high temperature tests have shown thermal resistance of around 570 0C with front wall temperature of 1186 0C and back wall of 533 0C. Also these panels have been characterized for reusability by the testing of same panel at different heat flux levels. Though it is found that honeycomb panel has shown its integrity without debond a certain acceptable level of degradation in coating is observed. Thus Inconel718 based honeycomb panels with TBC coating are proved for use as thermal protection system for reusable launch vehicle systems.

Abstract: Functionally graded coating material (FGM) based on yttria-stabilized zirconia (YSZ) and Ni-Cr-Al-Y was designed and developed for metallic thermal protection system of reusable launch vehicle (RLV). Coating was made using premixed mechanically alloyed YSZ and Ni-Cr-Al-Y powders through plasma spray technique. Thermal stress analysis was carried out, which showed significant reduction in stress in FGM coating as compared to dual coating. The phase composition of coating was found to be close to the designed one. Porosity varied in the range of 8-18%. Average emissivity of three different time exposures of 30, 60 and 90 s was found to be 0.8. Solar absorptivity was found to be 0.55. Fatigue life of FGM coating evaluated along with Inconel and Ti6Al4V metallic substrate was compared with dual coating. FGM coating could be fatigue tested to relatively higher thermal cycles as compared to dual coating on the Inconel substrate. Heat flux measured at top surface was found to be close to simulated heat flux for windward side of RLV. Top surface temperature was similar for both type of metallic substrates and was matching with predicted temperature. However, substrate temperature was higher for Ti6Al4V as compared to Inconel alloy due to higher thermal diffusivity of Ti6Al4V.

3. Project : ‘Thermostructural Analysis of Metallic Thermal Protection System’: Sponsored by Vikram Sarabhai Space Centre, Thiruvananthapuram, Indian Space Research Organisation, 2008-09. Manned space missions returning to the Earth require thermal protection system to absorb the thermal energy due to aerodynamic heating. Of the four mechanisms of thermal protection: (i) heat sink, (ii) cooling, (iii) surface insulation and (iv) ablation, the third one is considered suitable for vehicles used in multiple missions, such as space shuttle. In order to avoid / reduce damage, requiring extensive repair before next flight, metallic thermal protection systems (MTPS) are considered suitable. ISRO is presently involved in the design and development of MTPS for its Re-usable Launch Vehicle (RLV) programme. A finite element method based software has been developed as a design tool to carry out thermal and structural analyses of MTPS.

4. Patent: Title of Invention MANUFACTURING PROCESS TO REALIZE LIGHTWEIGHT INCONEL-718 PANELS FOR METALLIC THERMAL PROTECTION SYSTEMAbstract ABSTRACT "A method of manufacturing lightweight, honeycomb metallic thermal protection panels." This invention relates to lightweight honeycomb metallic thermal panels, which are reusable, heat resistant and are useful in making aerospace vehicle parts. Structures made from such panels are capable of with standing temperature conditions at re-entry of space vehicles. These panels are made from honeycomb structures made from thin corrugated films of super alloys like NiCr alloy Titanium Aluminize and the like which are laser welded to form honey comb structures of the desired thickness. They are then sandwiched between two face plates, which are treated to withstand oxidation.

As far as choice of design is concerned, ISRO must have chosen the design based on required mission profile, respective aerodynamic challenges involved and over all cost analysis of different configuration. Its nothing to do with looks.

Thanks Antriksh! I remembered reading a media-piece sometime back on ISRO's design philosophy focusing on metal ablatives, especially Chromium based ones. The selection of papers you quoted shows their progress nicely. I wonder if they're investigating TBCs on pre-stressed faceplates. With those honeycomb panels, it should be interesting.

Btw, is are there some consolidated online resources for ISRO's vehicle development research that I'm not aware of? Or was that some your dedicated google-fu, crawling through several personal research pages of PIs on their various institute websites?

I read the update about a new manufacturing route for the nose cap CC laminates, but any news on the TPS testing? Actually, any details of the TPS at all? How re-usable is it intended to be?

The flight profile of the TSTO is also intriguing.1) Why is the 1st stage the winged booster, and the upper stage the grasshopper? Why not vice versa? Some benefit of the aerodynamic lift to the curvilinear trajectory followed in ascent?

First stage needs to travel back to the launch site (or some friendly landing base).

Wings help this nicely, can turn and glide aerodynamically.

Second stage can stay in orbit long enough so that it can pass over the launch site and land to same site without need for long-distance aerodynamic gliding.

Shuttle orbiter did not need those big wings for missions it was used, it had those because DoD wanted to be able to do single-orbit reconnaissance missions over soviet union from Vandenberg.

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2) Why is there a different flyback mechanism for the upper stage, and the lower stage booster in any case? As it is, the diagram shows the first stage reaching altitudes+velocities where thermal protection becomes necessary for re-entry (unlike the recoverable, and reusable shuttle SRBs). Why not add a smaller version of the first stage on top of it instead of a grasshopper? I would think that two different technologies leads to increased design and development (if not operational also) costs.

Because the those wings on second stage would add extra weight that would reduce the payload weight. And bigger thermal shield would be needed.

Also, those wings would add extra aerodynamic drag in the beginning of the ascent.

First stage may needs _some_ thermal shielding, but lighter because it's re-entering at much lower speed that the second stage.

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Among those two, I'm biased to winged flyback over a vertical landing: cross range ability, possibly cheaper (propellant wise) control during ascent, and... well, they look the part of flying machines too

If cross-range is not needed, then it's not needed.

And I don't understand your point of aerodynamic control during ascent. The first stage can do it without the second stage, so having or not having aero surfaces on the second stage has nothing to do with it.

You contend that the wings on the second stage would add drag and extra weight. But the second stage flyback booster would have to carry propellant with it too - the weight of the wings substitute that. Sure, there might be more aerodynamic drag, but you can exploit that for propellant-less steering of the vehicle on its ascent. You can maintain control with first AND second stages. It adds redundancy if nothing else. Also, it seems a lot more complicated to have to store propellant over several orbits, through the thermal and dynamic conditions of re-entry and then ensuring the functionality of an engine soon after (in contrast to relatively passive aerodynamic surface control).

As regards the different levels of thermal shielding required: that may be true, but I'm sure that there are conventional cost savings if both stages' TPS systems derive from (if not use) the same technology and architectures. The simplicity of the supply chain - from design, manufacturing, tooling, integration, to the costs of training personnel etc. ought to be grow with similarity.

I'm sure that these and other concerns were accounted for, before they selected either type. I'd just like to go through the numbers that led to this design choice is all. The only clear winner would be if we go ahead and develop a TPS for the upper stage, which can withstand a capsule-like re-entry (aided only by parachutes for the final descent) AND IS ALSO re-usable (or design a capsule that can easily take on a new set of tiles/coating). Like a reusable Soyuz crew capsule.

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Btw, I don't understand what you mean about the shuttle's wings. The orbital (as opposed to sub-orbital) shuttle will come around over friendly territory of its own accord anyway - it doesn't have to have a glide ability. You might as well do it from Kennedy. If surprise, and ASAT missiles were key concerns, you could carry additional propellant for last minute orbit change/conjunction avoidance manoeuvres - and still stay below the required mass of a retrograde Vandenburg orbital launch.

Well, I think that a nice incidental benefit of all these different programs and efforts worldwide is the potential for a diversity of design configurations and combinations, which can then offer opportunity for comparisons through real-world performance and results.

While I certainly hope that SpaceX's F9R first stage is able to execute a glorious tail-first landing -- I really hope they telecast it live -- some people on the forum have expressed fears that it may tumble out of control. Wings at least seem to be a more familiar approach, and I'm thinking a more reliable one.

A large number of RLV concepts can be derived considering features like1) number of stages, 2) partial or full re-usability, 3) vertical or horizontal take-off / landing,4) tandem or parallel staging, 5) wing body or lifting body etc.

During the last decade extensive studies have been carried out in ISRO and based on detailed trade-off assessment, it was found that two stage to orbit configuration with a semi cryogenic winged booster and a cryogenic ballistic orbiter is the most feasible option considering the near term technologies.

One step at a time when you are doing it for the first time. first step is learning how the vehicle will behave during hypersonic flight. It will come to landing also in the LEX (drop and land experiment) and REX or return flight experiment (launch and land back).

Air data sensing system that uses flush pressure orifices embedded in the body. Pitot tubes are not suitable for hypersonic flight where the heat generated can destroy them.

NEURAL NETWORK BASED FLUSH AIR DATA SYSTEM (FADS) FOR REUSABLE LAUNCH VEHICLESAbstractFlush air data systems (FADS) are gaining importance for use in measurement of air data parameters like angle of attack, sideslip angle, Mach number and dynamic pressure for reentry and reusable vehicles, advanced aircrafts, interplanetary space probes etc. These air data parameters are critical for successful mission management of the vehicle during the flight phases dominated by complex aero thermal effects.

Flush Air Data System makes use of a matrix of flush pressure orifices located on the nose region (or stagnation region) of the vehicle to estimate air data parameters. The surface pressures are sensed using highly accurate absolute pressure transducers. The multivariable relationship between the pressure measurement and the output air data parameters is complex and highly nonlinear. Different methods are proposed in literature for the estimation of air data parameters using surface pressure measurements. Some of the earlier semi-empirical model based approaches used to process FADS pressure data have experienced numerical instabilities resulting in momentary degradation in system performance.

In this paper a neural network based FADS algorithm is developed for a reusable launch vehicle technology demonstrator. FADS is proposed to be used for the flight regime from Mach number 2.5 to 0. Neural networks, which require large quantities of training aerodynamic data set offer a simple, flexible and accurate solution for such complex applications. Neural network systems allow for the correlation of complex nonlinear systems without requiring explicit knowledge of the functional relationship that exists between the input and output variables of the system. Further, algorithms with neural network techniques are inherently stable for the calibration of nonlinear data involving more number of independent parameters.

The pressure port configuration used in this paper consists of nine pressure ports located on the nosecone of the vehicle. The pressure ports are arranged in a crucifix fashion with five ports located in the vertical meridian and four in the horizontal meridian. The pressure ports are connected to the pressure transducer using pneumatic tubing designed to satisfy frequency and thermal response requirements. The developed algorithm is validated using calibration data generated from wind tunnel tests. Back propagation technique is used to train the neural network to achieve the desired level of accuracy. The present study shows that with properly trained networks, the neural network can be used effectively for real-time prediction of air data states during the critical flight phases.

First stage: vertical launch powered by 3 semi-cryogenic engines (2000 kn each). Unpowered glide back to airstrip after separation around 100-150 km. RLV-TD programme to demonstrate the technologies involved in this stage development.

Second stage: Recoverable stage powered to orbit by cryogenic propulsion involving 2 cryogenic engines. Spacecraft/satellite separation by opening the cargo bay doors. Ballistic re-entry into the earth atmosphere and to be recovered at sea. SRE programme to demonstrate the technologies involved in the development of this stage

ISRO has research proposal for winged body re-entry as part of their RESPOND program:

Wing body reentry vehicle optimization studies (VSSC):Wing body reentry vehicle is a reusable launch vehicle concept to reduce the satellite launch vehicle cost drastically by safely returning the launch vehicle back to earth surface after the satellite/payload insertion in required orbit for re-launch. During reentry, the vehicle has to pass through low density atmosphere to high density atmosphere, High hypersonic Mach number to low subsonic mach number during touchdown and it alsoencounter viscous flow regime and pass through laminar to turbulent flow regimes. The key aerodynamic and aero-thermodynamic design aspects are optimum heat flux, heat load, load factor, less than 4g deceleration,sufficient payload bay, down range and cross range capability, good longitudinal and lateral- directional aerodynamic stability, adequate control surface effectiveness, reduced TOPS cost. The optimum externalaerodynamic design must fulfill some of the important objectives given above.

Re-entry module is used for scientific mission, or to bring back astronauts from space back to earth. Re-entry module can be a ballistic/or semi ballistic concept with minimum control. The key aerodynamic and aero thermodynamic parameters are minimizing the maximum heat flux, heat load and ‘g’ force with optimum stable aerodynamic shape for the purpose.

The module must be free from any dynamic stability issues, must have less dispersion in the down range and cross range, both soft landing on land and sea has to be considered within the design.

You mentioned reusable technology to save costs. Where are we in that?

Last year, we tried out the RLV-TD experiment [Reusable Launch Vehicle Technology Demonstrator]. We got a small, plane-like model to vertically land on water. Next we will look at landing it on the ground with a landing gear system. We are conceiving systems to work on the air breathing propulsion technology that will use atmospheric oxygen. For the present launch vehicles, we will look at recovering [and reusing] some parts.

So it sounds like the next experiment will be LEX - the Landing EXperiment - whereby the remaining twin RLV-TD model will be fitted with landing gear and landed on a runway. I'm assuming it will simply be dropped from an aircraft and not fired from a rocket, before deploying its landing gear to land conventionally. I think it's previously been mentioned that they might even possibly combine LEX with REX (Return flight EXperiment), the latter being where RLV-TD is fitted with a conventional turbojet, to take off from a runway conventionally and then land back on the runway conventionally, without being dropped from any carrier aircraft.

You mentioned reusable technology to save costs. Where are we in that?

Last year, we tried out the RLV-TD experiment [Reusable Launch Vehicle Technology Demonstrator]. We got a small, plane-like model to vertically land on water. Next we will look at landing it on the ground with a landing gear system. We are conceiving systems to work on the air breathing propulsion technology that will use atmospheric oxygen. For the present launch vehicles, we will look at recovering [and reusing] some parts.

So it sounds like the next experiment will be LEX - the Landing EXperiment - whereby the remaining twin RLV-TD model will be fitted with landing gear and landed on a runway. I'm assuming it will simply be dropped from an aircraft and not fired from a rocket, before deploying its landing gear to land conventionally. I think it's previously been mentioned that they might even possibly combine LEX with REX (Return flight EXperiment), the latter being where RLV-TD is fitted with a conventional turbojet, to take off from a runway conventionally and then land back on the runway conventionally, without being dropped from any carrier aircraft.

LEX will have drop tests first. The spare rocket for RLV-TD was built so not telling if it will be fired with LEX payload or fly with another stage as a sounding rocket.

Work is progressing at the Vikram Sarabhai Space Centre (VSSC) here on the second RLV-TD. A senior officer associated with the project said the RLV-TD will almost be a ditto version of the first scaled-down RLV-TD with the only exception being it will have landing gear

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ISRO sources said it may take another year for the model to be ready. They said the present plan is to launch the RLV-TD from Sriharikota and land it on an undisclosed Air Force airfield in the eastern sector. This is yet to be finalised though, they said.

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ISRO plans a series of TDs before attempting to build a fully-fledged vehicle that can be reused for launching satellites. A subsequent TD will possibly involve a slightly larger vehicle which will place a nano-satellite in the orbit.

I'm not sure if that last piece of info (if accurate) means they eventually plan to have a slightly scaled-up version of RLV-TD mounted on a larger solid booster and equipped with small liquid engines for orbit insertion, or whether they plan to mount it as a payload on a PSLV to test its re-entry characteristics from orbit.

They said the present plan is to launch the RLV-TD from Sriharikota and land it on an undisclosed Air Force airfield in the eastern sector. This is yet to be finalised though, they said.

IAF has a base in Andaman and Nicobar Islands. That might be a probable option as it pretty much lies in the direction of an eastward flight path from Sriharikota and is located at the right distance as well.

ISRO plans a series of TDs before attempting to build a fully-fledged vehicle that can be reused for launching satellites. A subsequent TD will possibly involve a slightly larger vehicle which will place a nano-satellite in the orbit.

I'm not sure if that last piece of info (if accurate) means they eventually plan to have a slightly scaled-up version of RLV-TD mounted on a larger solid booster and equipped with small liquid engines for orbit insertion, or whether they plan to mount it as a payload on a PSLV to test its re-entry characteristics from orbit.

I thought there were even going to be some kind of tests involving DMRJ (Dual-Mode-RamJet)I didn't hear about any scaled-up version for testing, though - I thought it was going to be this same vehicle being recovered, modified and re-flown for further tests.

They said the present plan is to launch the RLV-TD from Sriharikota and land it on an undisclosed Air Force airfield in the eastern sector. This is yet to be finalised though, they said.

IAF has a base in Andaman and Nicobar Islands. That might be a probable option as it pretty much lies in the direction of an eastward flight path from Sriharikota and is located at the right distance as well.

I'm assuming that the future TSTO vehicle which will be developed from RLV-TD technology will itself be landing in the Andaman & Nicobar Islands, so it makes sense to have RLV-TD land there as well during testing.

Is this a new RLV-TD or the same one that was flown last year? The wings look burned but that might just be the lighting.

A new one - the first one was not planned to be recovered.

Yeah, it's a new one. As you say, the first one wasn't planned to be recovered, although aircraft sent to the ocean touchdown site said they did see that the RLV-TD had touched down on the ocean surface intact, after which it sank beneath the waves. I wonder if that original model could somehow be salvaged? It could make for a decent museum piece.

"Our research and development department is working on three technology demonstrators. First one on the orbital re-entry of the vehicle, second on the landing of the reusable launch vehicle on the airstrip and third on reusable rocket stages. Isro's research work on these three technologies is simultaneously going on and we hope to do a second technology demonstrator test (first experiment on reusable launch vehicle was in 2016) within two years."

The Indian Space Research Organisation (ISRO) will soon carry out another major test for its reusable launch vehicle (RLV) in which the vehicle will be flown to a height of 3 km by a helicopter and let free to land autonomously at an airstrip in Challakere in Chitradurga district.

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This would be the second test for the vehicle after the first one in 2016 demonstrated that the RLV could land autonomously in the sea after being taken to an altitude of 65 km. Talking about the upcoming test, S Somanath, Director of the Vikram Sarabhai Space Centre, said the test will be carried out at the airstrip, owned by the Defence Research and Development Organization within 6 months. "After this test, we will integrate the vehicle into a new rocket which will take it up into orbit for it to return," he said.

In a bid to fulfil its dream of the manned mission, Indian Space Research Organisation (Isro) is gearing up for the second demonstration test of the reusable launch vehicle (RLV) next year. However, this time, the RLV will be tested on an airstrip and not on the sea.

Isro chairman K Sivan said, "We will conduct an RLV test sometime next year where a helicopter will take the vehicle to a height of 3 km and from that height, it will be dropped. The RLV will then glide and land on an airstrip."

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Isro conducted the first demonstration test of India's winged body aerospace vehicle on May 23, 2016. A solid rocket booster carrying RLV-TD lifted off from Sriharikota and coasted to a height of 56km. At that height, RLV-TD separated from HS9 booster and further ascended to a height of 65km and then started its descent and successfully glided down to the defining landing spot over the Bay of Bengal.

Sivan said, "The third experiment will include testing the RLV from the orbit. The vehicle will be integrated into a new rocket, which will take it up to the orbit. There, the vehicle will get detached and re-entre the earth's atmosphere and land."

I think the Indian media are once again mangling perceptions, by mentally associating the RLV-TD and its objectives with those of the very famous US Space Shuttle program. ISRO has never indicated that reusable launch technology development was particularly aimed at manned spaceflight. Perhaps it one day could be, if future use of this technology proves successful - but all previous roadmaps seemed to show RLV being developed primarily for low-cost satellite delivery to orbit.